Here's a few sites that have done a preview of Matrox's new Parhelia 512 card. Unfortunately Matrox has not yet provided any test samples for reviewers so all info is based on Matrox in-house PR!

Digit-Life

Hot Hardware

HardOCP

AnandTech or you might want to check out Matrox's Graphics Media Center for great images like this one below! or a bucket load of flash demos!